Electrospun cactus mucilage nanofibers

ABSTRACT

Novel electrospun nanofibers and nanofibrous membranes, methods of manufacturing the same, and methods of using the same are provided. The nanofibers include a cactus mucilage, such as mucilage from  Opuntia ficus - indica . An organic polymer can be added to the cactus mucilage before electrospinning. The nanofibrous membranes can be used in water filtration.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 61/501,010, filed Jun. 24, 2011, which is hereby incorporated byreference in its entirety including any tables, figures, or drawings.

GOVERNMENT SUPPORT

This invention was made with government support under grant number1057897 awarded by the National Science Foundation. The government hascertain rights in the invention.

BACKGROUND OF THE INVENTION

Water is fundamental for life on earth, and clean water is a necessityfor everyone. Access to clean water is necessary for continuity of ahealthy life. Unfortunately, getting clean water is a hardship manypeople still face. Although access to potable water has improved in thelast hundred years, communities in developing countries are stillaffected by unhygienic drinking water. About 1.1 billion people indeveloping countries struggle with the challenge of cleaningcontaminated water in their communities [1]. Additionally, 1.4 millionchildren die from diarrhea annually [1]. Many of these unfortunatedeaths could be prevented by increasing access to safe drinking water,but the process of cleaning contaminated water is sometimes difficultand costly.

Water is also essential in industries such as electronics,pharmaceuticals, and food [2]. Contaminants in water can be chemical orbiological, either naturally occurring in the environment or man-made.To help maintain global sustainability of human health and welfare, wemust develop ways to filter and clean our existing water resources. Ofparticular interest is the filtration of environmental contaminants withinexpensive, non-toxic, natural materials.

Since ancient times, people have tried different methods of cleaningwater. It has always been important to remove the smell, taste,turbidity, metals, and pathogens that can exist in water [3]. Some ofthe methods to reduce contamination in water include sedimentation,chemical treatment, and filtration.

Sedimentation is a method of waiting for the particles in water tosettle to the bottom by means of gravity and then removing the cleansupernatant water. While this method has been used for thousands ofyears and is inexpensive, it is incapable of removing small microbes andmetals that remain in the water [3].

Chemical treatment is also used to kill off viruses and bacteria livingin water. The chemicals most widely used are chlorine and iodine. Whilethese chemicals are easy to come by, getting the exact dosage todisinfect can be difficult. In addition, these chemicals are poisonousand adding too much in drinking water can cause illnesses, organ damage,and even death [4].

Filtration is commonly used in conjunction with sedimentation andchemical treatments [3]. Water filtration by definition means to siftout the impurities found in water. The size of the filtering pore isimportant to determine the size of particles that can be separated.Traditionally, filters can be made of sand, gravel, and charcoal. Newerfiltering methods are made from materials including ceramics and carbon.Many existing nanofiber meshes are made up of non-organic materials thatare not biodegradable.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the subject invention are drawn to novel electrospunnanofibers and methods of manufacturing the same. Embodiments are alsodrawn to methods of filtering contaminants from water using the novelelectrospun nanofibers.

In an embodiment, an electrospun nanofiber can include a cactusmucilage. The cactus mucilage can be, for example, Opuntia ficus-indica(Ofi) mucilage. The electrospun nanofiber can also include an organicpolymer.

In another embodiment, a nanofibrous membrane can include at least oneelectrospun nanofiber including a cactus mucilage. The cactus mucilagecan be, for example, Opuntia ficus-indica (Ofi) mucilage.

In anther embodiment, a method of producing an electrospun nanofiber caninclude: forming an electrospinning solution comprising a cactusmucilage and an organic polymer; and electrospinning the electrospinningsolution to form the electrospun nanofibril. Forming the electrospinningsolution can include: dissolving the cactus mucilage in a first solventto form a first solution; dissolving the organic polymer in a secondsolvent to form a second solution; and combining the second solution andthe first solution to form the electrospinning solution.

In another embodiment, a method of filtering contaminants from a fluidcan include: providing a nanofibrous membrane; and passing the fluidthrough the nanofibrous membrane, such that the nanofibrous membraneabsorbs at least one contaminant from the fluid. The nanofibrousmembrane can include at least one electrospun nanofiber comprising acactus mucilage. The fluid can be, for example, water.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a chart of filtration types versus size of commoncontaminants [5].

FIG. 2 shows naturally growing prickly pear cactus with flowers andfruit.

FIG. 3 shows the partial structure of Opuntia ficus-indica (Ofi)mucilage [13, 14].

FIG. 4 shows microscopic fluorescent images of E. coli with and withoutmucilage [27, 28]. (A) shows no mucilage and no CaCl₂; (B) shows nomucilage and CaCl₂ present at 20 mM; and (C) shows mucilage (2 ppm) andCaCl₂ present at 20 mM.

FIG. 5 shows a schematic of an electrospinning apparatus that can beused in a method of manufacturing electrospun nanofibers according to anembodiment of the present invention. A syringe pump is used forcontinuous feed of solution (adapted from [20]). The collector can beelectrically conductive, and the voltage can be on the order ofkilovolts (kV) or tens of kVs.

FIG. 6 shows SEM images of defects formed at lower levels of polymerconcentration [16].

FIG. 7 shows a chart of applications for electrospun nanofibers madeaccording to embodiments of the present invention [16].

FIGS. 8A and 8B show schematics of filtration members using a support orscaffold including electrospun nanofibers according to embodiments ofthe present invention [19].

FIG. 9 shows an extraction process flow for non-gelling mucilage.

FIG. 10 shows an SEM image of electrospun nanofibers according to anembodiment of the present invention. The magnification is 11K×. Thefeedstock was 9% PVA and mucilage in a ratio of 70:30 (PVA:mucilage).

FIG. 11 shows an SEM image of electrospun nanofibers according to anembodiment of the present invention. The magnification is 100K×. Thefeedstock was 9% PVA and mucilage in a ratio of 70:30 (PVA:mucilage).

FIG. 12 shows an SEM image of electrospun nanofibers according to anembodiment of the present invention. The magnification is 100K×. Thefeedstock was 9% PVA and mucilage in a ratio of 70:30 (PVA:mucilage).

FIG. 13 shows a microscopic image of electrospun nanofibers according toan embodiment of the present invention. The magnification is 50×. Thefeedstock was 9% PVA and mucilage in a ratio of 30:70 (PVA:mucilage).

FIG. 14 shows a microscopic image of electrospun nanofibers according toan embodiment of the present invention. The magnification is 100×. Thefeedstock was 9% PVA and mucilage in a ratio of 50:50 (PVA:mucilage).

FIG. 15 shows a microscopic image of electrospun nanofibers according toan embodiment of the present invention. The magnification is 1000×. Thefeedstock was 9% PVA and mucilage in a ratio of 70:30 (PVA:mucilage).

FIG. 16 shows a microscopic image of electrospun nanofibers according toan embodiment of the present invention. The magnification is 100×. Thefeedstock was 11% PVA and mucilage in a ratio of 70:30 (PVA:mucilage).

FIG. 17 shows a top view SEM image of electrospun nanofibers accordingto an embodiment of the present invention. The feedstock was 11% PVA andmucilage in a ratio of 70:30 (PVA:mucilage).

FIG. 18 shows an SEM image of electrospun nanofibers according to anembodiment of the present invention. The magnification is 70K×. Thefeedstock was 11% PVA and mucilage in a ratio of 70:30 (PVA:mucilage). Afiber diameter measured about 52 nm.

FIG. 19 shows an SEM image of electrospun nanofibers according to anembodiment of the present invention. The magnification is 6K×. Thefeedstock was 11% PVA and mucilage in a ratio of 70:30 (PVA:mucilage).The fiber diameter measured about 7.8 μm.

FIG. 20 shows AFM images at 10 μm of electrospun nanofibers according toan embodiment of the present invention. The feedstock was 9% low M PVAand mucilage in a ratio of 70:30 (PVA:mucilage).

FIG. 21 shows AFM images at 1 μm of electrospun nanofibers according toan embodiment of the present invention. The feedstock was 9% low M PVAand mucilage in a ratio of 70:30 (PVA:mucilage).

FIG. 22 shows an AFM Sectional Analysis at 1 μm of electrospunnanofibers according to an embodiment of the present invention. Thefeedstock was 9% low M PVA and mucilage in a ratio of 70:30(PVA:mucilage). The fiber diameter measured about 177 nm.

FIG. 23 shows AFM images at 10 μm of electrospun nanofibers according toan embodiment of the present invention. The feedstock was 9% high M PVAand mucilage in a ratio of 70:30 (PVA:mucilage).

FIG. 24 shows AFM images at 1 μm of electrospun nanofibers according toan embodiment of the present invention. The feedstock was 9% high M PVAand mucilage in a ratio of 70:30 (PVA:mucilage).

FIG. 25 shows a Sectional Analysis at 1 μm of electrospun nanofibersaccording to an embodiment of the present invention. The feedstock was9% high M PVA and mucilage in a ratio of 70:30 (PVA:mucilage). The fiberdiameter measured about 460 nm.

FIG. 26 shows a Sectional Analysis at 1 μm of electrospun nanofibersaccording to an embodiment of the present invention. The feedstock was9% high M PVA and mucilage in a ratio of 70:30 (PVA:mucilage). The fiberdiameter measured about 4 μm.

FIG. 27 shows a 3D AFM image at 1 μm of electrospun nanofibers accordingto an embodiment of the present invention. The feedstock was 9% low MPVA in a ratio of 70:30 (PVA:mucilage).

FIG. 28 shows a 3D AFM image at 1 μm of electrospun nanofibers accordingto an embodiment of the present invention. The feedstock was 9% high MPVA in a ratio of 70:30 (PVA:mucilage).

FIG. 29 shows a microscopic image of electrospun nanofibers according toan embodiment of the present invention. The magnification is 100×. Thefeedstock was 9% PVA and mucilage in a ratio of 30:70 (PVA:mucilage).

FIG. 30 shows (A) an image of an electrospinning experimental setup, and(B) a close-up image of a syringe and a collector plate.

FIGS. 31A and 31B show images of mucilage and PVA nanofiber meshesaccording to an embodiment of the present invention.

FIG. 32 shows a microscopic image of NaOH and mucilage nanofibers. Themagnification is 20×.

FIG. 33 shows mucilage nanofibers according to an embodiment of thepresent invention. The magnification is (A) 50× and (B) 100×.

FIG. 34 shows a plot of heat flow as a function of temperature forPVA-neat, PVA and high molecular weight mucilage, and PVA and lowmolecular weight mucilage.

FIG. 35 shows an image of a human hair follicle overlaid on a mucilagenanofiber mesh.

DETAILED DISCLOSURE OF THE INVENTION

Embodiments of the subject invention are drawn to novel electrospunnanofibers and methods of manufacturing the same. Embodiments are alsodrawn to methods of filtering contaminants from water using the novelelectrospun nanofibers.

The term “about,” as used herein before a measured value, refers towithin measurement error of the value following the term “about,”typically +/−5% of the value (for example, “about 750 nm” refers to712.5 nm to 787.5 nm).

FIG. 1 shows types of filtering processes including conventionalfiltration, microfiltration, ultrafiltration, nanofiltration, andreverse osmosis, as well as the size of contaminants that can befiltered using each process.

For filtration processes, the size of the pores in the filters dictatesthe size of the materials that can be filtered out of the water.Nanofiltration and reverse osmosis are able to remove very smallparticles (e.g., 0.001 micron-sized), including pesticides, dyes, andother organic contaminants. Reverse osmosis is generally used inconjunction with carbon filtration for desalination processes, butreverse osmosis requires a large amount of energy to operate and wateris lost in the process, along with dissolved naturally-occurringminerals that are needed for human nutrition.

Nanofiltration can be thought of as a combinatory process capable ofremoving hardness and a wide range of other components in one step. Thesmall membranes used in nanofiltration have the advantages ofcompactness, low-cost operation, energy-efficiency, and high throughput.While most commercially available membranes are made with syntheticmaterials and are not biodegradable, nanofibrous membranes producedaccording to embodiments of the present invention can include onlyorganic materials and can be biodegradable. Table 1 shows an overview ofsome existing nanofiltration membranes by manufacturer and composition.

TABLE 1 Overview of Commercial Nanofiltration Membranes Membrane UTC20Desal5DL Desal51HL NTR7450 N30F NFPES10 Manufacturer Toray^(a) GEOsmonics^(b) GE Osmonics^(b) Nitto-Denko^(c) Nadir^(d) Nadir^(d) MWCO(Da) 180 150-300 150-300 600-800 400 1000 Max. temp (° C.) 35 90 50 40 95  95 pH range 3-10  1-11 3-9  2-14 0-14 0-14 Composition topPolypipera- Cross-linked Cross-linked Sulfonated Permanently Permanentlylayer zineamide aromatic aromatic polyether- hydrophilic hydrophilicpolyamide polyamide sulfone polyether- polyether- sulfone sulfone^(a)Tokyo, Japan; ^(b)Le Mee sur Seine, Frankrijk; ^(c)Somicon AG,Basel, Switzerland; ^(d)Wiesbaden, Germany.

Filtration membranes are important components and highly utilized inwater purification, waste treatment, and in clarification andconcentration processes. Nanofiltration is an important method that canbe used in industrial and public water purification systems. Synthesisof cost-effective and environmentally-acceptable functional materials,such as with embodiments of the present invention, can help providelow-cost, efficient, environmentally-acceptable water purificationsystems. The present invention provides environmentally friendly,non-toxic, and biodegradable methods of water treatment. It alsoprovides sustainable technologies for water filtration that areeconomically competitive and affordable.

In an embodiment, an electrospun nanofiber can include a cactusmucilage. The cactus mucilage can be, for example, Opuntia ficus-indica(Ofi) mucilage. The electrospun nanofiber can also include an organicpolymer.

In another embodiment, a nanofibrous membrane can include at least oneelectrospun nanofiber including a cactus mucilage. The cactus mucilagecan be, for example, Opuntia ficus-indica (Ofi) mucilage.

In anther embodiment, a method of producing an electrospun nanofiber caninclude: forming an electrospinning solution comprising a cactusmucilage and an organic polymer; and electrospinning the electrospinningsolution to form the electrospun nanofibril. Forming the electrospinningsolution can include: dissolving the cactus mucilage in a first solventto form a first solution; dissolving the organic polymer in a secondsolvent to form a second solution; and combining the second solution andthe first solution to form the electrospinning solution.

In another embodiment, a method of filtering contaminants from a fluidcan include: providing a nanofibrous membrane; and passing the fluidthrough the nanofibrous membrane, such that the nanofibrous membraneabsorbs at least one contaminant from the fluid. The nanofibrousmembrane can include at least one electrospun nanofiber comprising acactus mucilage. The fluid can be, for example, water.

In embodiments, cactus mucilage can be used as a component of afeedstock used to produce non-woven nanofibers. These non-wovennanofibers can be spun using an electrospinning technique.Electrospinning is a safe, simple, cost-effective, and reliable methodof producing nanofiber meshes. FIG. 35 shows an image of a human hairfollicle overlaid on a nanofiber mesh. Mucilage from any cactus can beused as a component of a feedstock used to electrospin nanofibers. Forexample, mucilage from the Opuntia ficus-indica (Ofi), also known as theprickly pear, can be used. Ofi is an abundant plant that can be foundalmost anywhere in the world. FIG. 2 shows a picture ofnaturally-growing Ofi with flowers and fruit. In certain embodiments,mucilage from aloe vera or okra can be used. In an embodiment, cactusgoo can be used as a component of a feedstock used to produce anelectrospun nanofiber.

The genus Opuntia is the largest under the Cactaceae family [11].Domestication of Ofi started in Mexico about 9000 years ago [12]. Afterthe colonization of the Americas, the Ofi plant was introduced to Spainand then the rest of the Mediterranean [12]. Varieties of Opuntia cannow be found all around the world [11].

Ofi or prickly pear is a very versatile plant. Ofi leaves and fruitshave been used in rural Mexico for their medicinal benefits, such as fortreating atherosclerosis, diabetes, and gastritis and hyperglycemia[11]. Studies have been made to use the prickly pear for cultivation asan alternative to cereal and forage crops. The fruits of the cactus wereto be used for human consumption and the green pads for livestockfeeding [13]. The cactus has been also studied for its antioxidantproperties.

The mucilage inside the Ofi plant is a thick, gummy, clear substance.Like mucilage from other plants, it aids in retaining and storing waterfor the cactus. Mucilage can swell when in contact with water, giving itthe ability to precipitate ions and particles from aqueous solutions.Most of the mucilage is found in the cladodes or pads of the cactus. Themucilage content in the cladodes is influenced not only by the handlingof the crop but is also dependent on the temperature and irrigation[13].

Mucilage is a neutral complex carbohydrate composed of 55 sugar residuesincluding arabinose (67.3%), galactose (6.3%), rhamnose (5.4%), andxylose (20.4%), and a galacturonic acid [13, 14]. Cárdenas et al.states:

-   -   In general, they contain varying proportions of L-arabinose        (pyranose and furanose forms), D galactose, L-rhamnose and        D-xylose as the major neutral sugar units as well as        D-galacturonic acid. The suggested primary structure describes        the molecule as a linear repeating ‘core’ chain of (1→4)-linked        β-D-galacturonic acid and α(1→2)-linked L-rhamnose with        trisaccharide side chains of β(1→6)-linked D-galactose attached        at O(4) of L-rhamnose residues (McGravie and Parolis, 1981a).        The galactose side residues present further branching in either        O(3) or both O(3) and O(4) positions. The composition of these        acid-labile peripheral chains is complex, at least 20 different        types of oligosaccharides (mostly as di- and trisaccharides)        have already been identified (McGravie and Parolis, 1981b).        These invariably containing L-arabinose residues present as        (1→5)-linked residues and possibly as branch points (McGravie        and Parolis, 1981b) and single D-xylose groups occur as        end-groups, to give a xylose-to arabinose ratio of ˜1:2. This        chemical composition is similar to that of the highly branched        regions (‘hairy’ regions) of cell-wall pectins, particularly to        the rhamnogalacturonan I (RGI) fraction (Voragen et al. 1995;        Pellerin et al. 1996. Hence cactus mucilage is often referred to        as a pectin polysaccharides. Recently Forni et al. (1994),        reported a methoxyl degree and acetyl degree respectively of 10        and 10.4% in the pectin extract from the peel of prickly pear of        Opuntia ficus-indica.        Pp. 2-3. It also contains organic species which give the        capacity to interact with metals, cations and biological        substances such as K, Ca, Mg, Fe, Na, and others [13]. This        unique surface activity enhances dispersion, creates        emulsifications, and reduces tension of high polarity fluids.

FIG. 3 shows a partial structure of mucilage [13, 14]. R indicates thepresence of different arabinose and xylose forms, D-Gal indicatesD-galacturonic acid, Gal indicates galactose, and Rha indicates Rhamnose[13, 14, 5].

In embodiments of the subject invention, non-woven nanofibers can beproduced by electrospinning. Electrospinning is a simple and inexpensivemethod of fabricating nanofibers from synthetic or natural polymers. Inalternative embodiments, other methods can be used to producenanofibers, including template synthesis and phase separation. Templatesynthesis uses a nanoporous membrane as a template to make nanofibershapes, either hollow or solid. This method has the disadvantage of notbeing able to continuously create nanofibers. Phase separationnanofibers are created by dissolution, gelation, extraction withdifferent solvents, freezing, and drying, resulting in nanoscale porousfoam. This process has the disadvantage of taking a relatively longperiod of time to create the nanoscale porous foam [16].

In embodiments of the subject invention, non-woven nanofibers can beproduced by electrospinning FIG. 5 shows a schematic of anelectrospinning apparatus that can be used in methods of manufacturingelectrospun nanofibers according to embodiments. A syringe pump can beused for continuous feed of solution over extended time periods. Thecollector is electrically conductive, and the voltage can be on theorder of kilovolts (kV) or tens of kVs. The high voltage source can beused to create a charged jet of polymer solution out of the syringe. Anelectrode can be placed on the needle and the collector can grounded,driving a high voltage electric field between them. The charged polymerscan evaporate and solidify into a network of tiny fibers that arecollected on the collector.

In an embodiment, a polymer solution can be used as the feedstock forelectrospinning Solutions of one or more polymers can be mixed bydissolving one or more solid polymers with one or more appropriatesolvents. Mixtures are different depending on the polymer, but onceliquid is attained, it can be transferred to a syringe with needle. Thisdissolving process and the electrospinning can take place at anyappropriate temperature and pressure conditions. In an embodiment, thedissolving process and electrospinning can take place at roomtemperature at atmospheric conditions.

During the electrospinning process, a syringe pump can be used to helppush the polymer solution to the tip of the needle. A capillary can beformed and held at the end of the needle by surface tension. A DCvoltage supply of, e.g., several kilovolts can be used to create anelectric field between the needle tip and the collector. The electricfield helps to induce a charge on the surface of the liquid and causes aforce directly opposite to the surface tension directed towards thegrounded collector plate. Increasing the electric field forces thehemispherical shape of the capillary into a cone shape, known as aTaylor cone. A critical value is attained in which the electric fieldforce surpasses the surface tension, and the fluid is ejected from theTaylor cone tip. The polymer solution becomes unstable and elongates,allowing the jet to become very thin and long. The solvent(s) evaporate,leaving behind charged polymer fibers that solidify on the collectorplate. In some instances, calcination of the fibers is required. Theparameters of the electrospinning process can be varied to producenanofibers with different properties.

In an embodiment, the voltage can be in a range of from 5 kV to 30 kV.In a further embodiment, the voltage can be in a range of from 20 kV to22 kV. In a further embodiment, the voltage can be in a range of fromabout 20 kV to about 22 kV.

In an embodiment, the syringe inner diameter can be in a range of from0.1 mm to 10 mm. In a further embodiment, the syringe inner diameter canbe in a range of from 1 mm to 5 mm. In a further embodiment, the syringeinner diameter can be 4 mm or about 4 mm.

In an embodiment, the distance from the nozzle to the collector can bein a range of from 1 cm to 100 cm. In a further embodiment, thenozzle-collector distance can be in a range of from 5 cm to 15 cm. In afurther embodiment, the nozzle-collector distance can be in a range offrom 7 cm to 13 cm. In a further embodiment, the nozzle-collectordistance can be in a range of from about 7 cm to about 13 cm.

In an embodiment, the electric field strength can be in a range of fromabout 10² V/m to about 10⁶ V/m. In a further embodiment, the electricfield strength can be in a range of from about 1.5×10⁵ V/m to about3.5×10⁵ V/m. In a further embodiment, the electric field strength can bein a range of from about 1.53846×10⁵ V/m to about 3.14285×10⁵ V/m. Incertain embodiments, the electric field strength can be 1.53846×10⁵ V/m,1.61538×10⁵ V/m, 1.66666×10⁵ V/m, 1.69230×10⁵ V/m, 1.75000×10⁵ V/m,1.81818×10⁵ V/m, 1.83333×10⁵ V/m, 1.90909×10⁵ V/m, 2×10⁵ V/m, 2.1×10⁵V/m, 2.2×10⁵ V/m, 2.22222×10⁵ V/m, 2.33333×10⁵ V/m, 2.44444×10⁵ V/m,2.5×10⁵ V/m, 2.625×10⁵ V/m, 2.75×10⁵ V/m, 2.85714×10⁵ V/m, 3×10⁵ V/m, or3.14285×10⁵ V/m.

In an embodiment, the infusion rate of the prepared solution (e.g.,feedstock solution) can be in a range of from 1 μL/min to 100 μL/min. Ina further embodiment, the infusion rate of the feedstock solution can bein a range of from 1 μL/min to 10 μL/min. In a further embodiment, theinfusion rate of the feedstock solution can be 2.5 μL/min or about 2.5μL/min. The needle size can be, for example, 18-½″ gauge or 22-1″ gauge.The syringe size can be, for example, 1 mL.

In embodiments, an electrospinning feedstock includes a co-spinningpolymer added to cactus mucilage. The co-spinning polymer can helpinitiate forming the polymer chains needed for nanofiber formation. Theco-spinning polymer can be any appropriate polymer used forelectrospinning, for example, an organic polymer. Examples of organicpolymers that can be used include, but are limited to, chitosan,polyethylene glycol (PEG), poly lactic acid (PLA), and polyvinyl alcohol(PVA). PVA is a water soluble polymer that is odorless, non-toxic,biodegradable, and biocompatible. It is also resistant to oil andsolvents and has high tensile strength and flexibility. When spinningPVA as a co-spinning agent with carbohydrates it is important to monitorthe concentration and ratios of carbohydrates to PVA. The percentconcentration of the solution should be closely monitored to achievelower-defect or defect-free fibers. If the polymer concentration is toolow, many defects or no fibers may be formed. The viscosity of thesolution is related to the number of polymer chains in the solution.FIG. 6 shows SEM images of defects formed at lower levels of polymerconcentration (increasing concentration to the right—giving less beads).

In an embodiment, the cactus mucilage can be dissolved in a solvent. Thecactus mucilage solution can then be combined with an organic polymer toform the feedstock for electrospinning Any appropriate solvent can beused to dissolve the cactus mucilage, for example, acetic acid (AA) oran aqueous solution including AA. AA is a weak acid that can easily bediluted and still be harmless and biocompatible when mixed with mucilage(and with PVA).

In many embodiments, electrospun nanofibers according to the presentinvention can each have a diameter of less than a micron. In alternativeembodiments, the fibers can have a diameter of more than a micron orabout a micron. In an embodiment, the fibers can have a diameter in arange of from 10 nm to 20 μm. In a further embodiment, the fibers canhave a diameter in a range of from 10 nm to 10 μm. In a furtherembodiment, the fibers can have a diameter in a range of from 50 nm to 8μm. In certain embodiments, the fibers can have a diameter of 52 nm,about 52 nm, 177 nm, about 177 nm, 180 nm, about 180 nm, 4 μm, about 4μm, 7.8 μm, or about 7.8 μm.

In an embodiment, the solution used for electrospinning can include amucilage and an organic polymer. The mucilage and the organic polymercan be present in the solution in a ratio of, for example, 70:30(polymer:mucilage). In an embodiment, the percentage of the organicpolymer in the electrospinning solution can be a range of from 1% to99%. In a further embodiment, the percentage of the organic polymer inthe electrospinning solution can be a range of from 5% to 95%. In afurther embodiment, the percentage of the organic polymer in theelectrospinning solution can be a range of from 10% to 95%. In a furtherembodiment, the percentage of the organic polymer in the electrospinningsolution can be a range of from 30% to 95%. In a further embodiment, thepercentage of the organic polymer in the electrospinning solution can bea range of from 50% to 95%. In a further embodiment, the percentage ofthe organic polymer in the electrospinning solution can be a range offrom 70% to 95%. In a further embodiment, the percentage of the organicpolymer in the electrospinning solution can be a range of from 50% to90%.

In an embodiment, the solution used for electrospinning can include amucilage and an organic polymer. An organic polymer solution can becombined with a solution including the mucilage to form theelectrospinning solution. The organic polymer solution can include theorganic polymer in a percentage of, for example, 7%, 9%, 11%, or 20%. Inan embodiment, the organic polymer solution can include the polymer in apercentage of from 7% to 50%. In a further embodiment, the organicpolymer solution can include the polymer in a percentage of from 9% to20%. In a further embodiment, the organic polymer solution can includethe polymer in a percentage of from 9% to 15%.

Electrospun nanofibers are advantageous because of their small diameter,large surface area per unit mass, extremely small pore size, andsuperior mechanical properties. These features make them an idealmaterial for many applications. The mucilage nanofibers according toembodiments of the present invention have many advantageous uses,including but not limited to: water filtration; air and gas filtration;absorption; sensors; tissue scaffolding; tissue engineering; drugdelivery; catalysts; enzyme carriers; food additives; textiles; and MEMSdevices. FIG. 7 shows a chart of several uses for nanofibers of thepresent invention. Water filtration systems using nanofibrous membranesincluding mucilage nanofibers of the present invention canadvantageously be affordable, biodegradable, sustainable, and can beutilized worldwide to help millions.

Ofi mucilage is a versatile and unique substance. Nanofiber meshesproduced from this mucilage can be used for biodegradable water filters.Ofi mucilage can advantageously remove bacteria from water. FIG. 4 showsmicroscopic fluorescent images of E. coli with and without mucilage. (A)shows no mucilage and no CaCl₂; (B) shows no mucilage and CaCl₂ presentat 20 mM; and (C) shows mucilage (2 ppm) and CaCl₂ present at 20 mM.

The electrospun nanofibrous membranes of the present invention possessseveral attributes that make them very attractive in water filtrationtechnology. These include, but are not limited to, high porosity, poresizes ranging from tens of nanometers to several micrometers,interconnected open pore structure, and a large surface area per unitvolume. FIG. 8 shows a depiction of filtration membranes using ananofibrous scaffold as a nanofibrous membrane.

EXEMPLIFIED EMBODIMENTS

The invention includes, but is not limited to, the followingembodiments:

Embodiment 1

An electrospun nanofiber, including a cactus mucilage.

Embodiment 2

The electrospun nanofiber according to embodiment 1, wherein the cactusmucilage is Opuntia ficus-indica (Ofi) mucilage.

Embodiment 3

The electrospun nanofiber according to any of embodiments 1-2, furtherincluding an organic polymer.

Embodiment 4

The electrospun nanofiber according to embodiment 3, wherein the organicpolymer is polyvinyl alcohol (PVA).

Embodiment 5

A nanofibrous membrane, including at least one electrospun nanofiberaccording to any of embodiments 1-4.

Embodiment 6

A method of producing an electrospun nanofiber, including:

-   -   forming an electrospinning solution including a cactus mucilage        and an organic polymer; and    -   electrospinning the electrospinning solution to form the        electrospun nanofibril.

Embodiment 7

The method according to embodiment 6, wherein forming theelectrospinning solution includes:

-   -   dissolving the cactus mucilage in a first solvent to form a        first solution;    -   dissolving the organic polymer in a second solvent to form a        second solution; and    -   combining the second solution and the first solution to form the        electrospinning solution.

Embodiment 8

The method according to any of embodiments 6-7, wherein the cactusmucilage is Opuntia ficus-indica (Ofi) mucilage.

Embodiment 9

The method according to any of embodiments 6-8, wherein the organicpolymer is polyvinyl alcohol (PVA).

Embodiment 10

The method according to embodiment 9, wherein the organic polymer isPVA.

Embodiment 11

The method according to any of embodiments 7-10, wherein the firstsolvent includes acetic acid.

Embodiment 12

The method according to any of embodiments 6-11, wherein electrospinningthe solution includes electrospinning the solution in an electric fieldof from about 1.5×10⁵ V/m to about 3.5×10⁵ V/m.

Embodiment 13

The method according to any of embodiments 7-12, wherein the secondsolvent is water.

Embodiment 14

The method according to any of embodiments 6-13, wherein theelectrospinning solution includes the organic polymer and the cactusmucilage present in a ratio of 70:30 (polymer:mucilage).

Embodiment 15

The method according to any of embodiments 6-13, wherein theelectrospinning solution includes the organic polymer and the cactusmucilage present in a ratio of 50:50 (polymer:mucilage).

Embodiment 16

The method according to any of embodiments 7-15,

-   -   wherein the cactus mucilage is Ofi mucilage,    -   wherein the organic polymer is PVA, and    -   wherein the second solution includes 9% (w/w) PVA.

Embodiment 17

The method according to any of embodiments 7-16, wherein the secondsolution is a 28.4 M 9% PVA solution.

Embodiment 18

The method according to any of embodiments 7-16, wherein the secondsolution is an 80 M 9% PVA solution.

Embodiment 19

The method according to any of embodiments 7-14,

-   -   wherein the cactus mucilage is Ofi mucilage,    -   wherein the organic polymer is PVA, and    -   wherein the second solution includes 11% (w/w) PVA.

Embodiment 20

The method according to any of embodiments 7-14 and 19, wherein thesecond solution is a 28.4 M 11% PVA solution.

Embodiment 21

A method of filtering contaminants from a fluid, including:

-   -   providing a nanofibrous membrane; and    -   passing the fluid through the nanofibrous membrane, such that        the nanofibrous membrane absorbs at least one contaminant from        the fluid,    -   wherein the nanofibrous membrane comprise at least one        electrospun nanofiber including a cactus mucilage.

Embodiment 22

The method according to embodiment 21, wherein the fluid is water.

Embodiment 23

The method according to any of embodiments 21-22, wherein the cactusmucilage is Opuntia ficus-indica (Ofi) mucilage.

Embodiment 24

The method according to any of embodiments 21-23, wherein the at leastone electrospun nanofiber further includes an organic polymer.

Embodiment 25

The method according to embodiment 24, wherein the organic polymer ispolyvinyl alcohol (PVA).

Materials and Methods

FIG. 9 shows a process flow for a procedure for extracting mucilage fromthe Opuntia-ficus indica (Ofi). The pad of the cactus can be washed withhard water and deionized water and then dried. The pad can then besliced in, e.g., half-inch squares and placed into a beaker. A 1% w/wsolution of NaCl can be poured into the beaker until the cut mucilage iscovered. The beaker can then be heated on a hot plate and set to 300° C.or about 300° C. until the solution boils. The temperature can then belowered to 200° C. or about 200° C. and then cooked for another 20minutes, stirring occasionally. The cactus pads change color from abright green to an olive green color when cooked. Stirring occasionallyhelps to ensure even heating.

The mixture can then be set to cool and then liquidized in a blender.The pH of the mixed solution at this time should be about 4. The pH ofthe mixed solution can then be neutralized to a pH of 7 or about 7 with,e.g., a 1 M solution of NaOH. The neutralized cactus mixture can then becentrifuged at 3,000 rpm for about 5 minutes. The supernatant can beseparated as the non-gelling extract (NE), and the solid is the gellingextract (GE). For the examples provided herein, only the NE was used,though embodiments of the present invention are not limited thereto.

The supernatant can be mixed with NaCl for a 1 M solution. It can thenbe vacuum-filtered using, e.g., filter paper number 41. The filteredliquid can then be mixed with acetone in a one to one ratio (1:1) andleft covered under a ventilation hood overnight. The precipitate canthen be taken out and washed with ethanol solutions of 70, 80, 90, 95,and/or 100% v/v. The washed solid can then be left to dry covered in theventilation hood. Depending on the amount of mucilage extracted, thismay take 2 to 3 days to dry and can be placed in an oven at 50° C. for afew hours to accelerate the drying process. The resulting dried mucilagecan be put in a mortar and pestle to be grounded into powder form. Theresulting mucilage powder can be used to create nanofibers.

The mucilage power can be mixed at a 4% w/w with a solution of aceticacid (AA) and deionized water. The AA can be mixed with deionized waterat a 50% w/w. Mucilage and acid can be mixed at 60° C. (or about 60° C.)at 600 rpm and covered to avoid evaporation for 8-10 hours or until thesolution is a consistent mixture. A tissue grinder can be used to helpensure even mixture of the mucilage acid solution and to help prohibitthe formation of clusters and/or reduce the size of such clusters thatmay form.

The mucilage solution can be mixed with a polymer solution. The polymersolution can be, for example, polyvinyl alcohol (PVA). PVA can be usedat two different molecular weights. The lower molecular weight (28.4 M)can be mixed in four different concentrations—7%, 9%, 11%, and 20%. Thehigher molecular weight PVA (80 M) can be mixed at a 9% concentrationsolution. All solutions can be mixed with deionized water at 125° C. at900 rpm and covered for approximately 1.25 hours or until PVA hasthorough consistency.

A 4% w/w mucilage with a 50% w/w AA was achieved. There appeared to beno difference in fiber formation between using 90% w/w AA mix and using50% AA mix. The 50% w/w AA was less caustic. A tissue grinder was usedto get a good homogeneous mixture after several hours of magneticstirring.

A PVA solution can be mixed with a mucilage/AA mixture. PVA solutions atdifferent concentrations and molecular weights can be mixed withmucilage/AA mixtures to give different ratios of PVA:mucilage. Forexample, a 9% PVA solution can be mixed by volumetric ratios of 70:30,50:50, and 30:70 (PVA:mucilage) with mucilage for the lower molecularweight of 28.4 M PVA. The higher molecular weight PVA of 80 M can bemixed at a ratio of 70:30 (PVA:mucilage) with the mucilage solution.Table 2, which should not be construed as limiting, shows examples ofPVA solutions and resulting PVA:mucilage ratios that can be used. Theexamples shown in Table 2 were used for the examples provided herein.Each of these mixtures was heated to 60° C. at 600 rpm for about 30minutes.

TABLE 2 PVA and Mucilage Ratio Mixtures Ratios (PVA:Mucilage) PVA(28.4M) 7% 70:30 9% 70:30 50:50 30:70 11%  70:30 PVA (80M) 9% 70:30

Achieving a well-mixed PVA can be difficult at some percentages. PVA at7%, 9%, and 11% were used for the examples provided herein. The 20%solution of the lower MW PVA was too thick and burned before beingthoroughly mixed. Table 4, which should not be construed as limiting,shows characteristics of examples of PVA solutions that can be used. Theexamples shown in Table 3, except for the 20% 28.4 M solution, were usedfor the examples provided herein.

TABLE 3 PVA Experimental Mixtures PVA 28.4M  7% good solution  9% goodsolution 11% good solution 20% solution did not mix PVA 80M  9% goodsolution

The PVA and mucilage solutions were mixed together but it was observedthat after several hours the mucilage and PVA would start to separate.More mixing and agitation would bring them back together.

The resulting PVA/mucilage mixture can be used as feedstock forelectrospinning to produce electrospun nanofibers. The electrospinningfield can be set inside an enclosed box to reduce electrostaticinterference, other electric fields, and other factors that may impedethe optimum formation of fibers. FIG. 5 shows a schematic of anelectrospinning apparatus that can be used according to embodiments ofthe present invention. A syringe pump can be used for continuous feed offeedstock solution over extended time periods. The collector can beelectrically conductive, and the voltage can be on the order ofkilovolts (kV) or tens of kVs. For the examples provided herein, thepower supply used was a Spectrovision DA-30. The syringe pump was aHarvard Apparatus PHD 2000. FIG. 30A shows a view of the experimentalsetup, and FIG. 30B shows a close-up of a syringe and collector plate.

For the examples provided herein, the parameters for electrospinningwere set as shown in Table 4. Earlier experiments showed that theparameters were advantageous for to produce good nanofibers. Thedistance between the needle tip and collector plate was varied toproduce differences in fiber diameter and shape. The values given inTable 4 are examples of values for the parameters that can be usedaccording to embodiments of the subject invention and should not beconstrued as limiting.

TABLE 4 Parameters Set for Electrospinning Setup ElectrospinningParameters Values Voltage 20~22 kV Syringe 1 mL Syringe Diameter 4 mmNeedle* 18½″ gauge 22 1″ gauge Infusion Rate 2.5 μL/min Distance (needletip and collector plate)* 7-13 cm *Changed between experiments

Nanofibers were characterized using a Scanning Electron Microscope,Atomic Force Microscopy, and Differential Scanning Calorimetry.

EXAMPLES

Following are examples that illustrate procedures for practicing theinvention. These examples should not be construed as limiting.

Example 1 7% PVA and Mucilage in a Ratio of 70:30 (PVA:Mucilage)

A 7% PVA solution and mucilage in a ratio of 70:30 (PVA:mucilage) wasused for electrospinning No fibers formed and it was difficult tocapture images of the dots and deformities that formed.

Example 2 9% PVA and Mucilage in a Ratio of 30:70 (PVA:Mucilage)

A 9% PVA solution and mucilage in a ratio of 30:70 (PVA:mucilage) wasused for electrospinning Although some fibers formed, there appeared tobe not enough polymer mixtures because there were many dots anddeformities. FIG. 13 shows a microscopic image of beads and fewelectrospun nanofibers formed from electrospinning a feedstock of 9% PVAand mucilage in a ratio of 30:70 (PVA:mucilage). The magnification is50×. FIG. 29 also shows a microscopic image of beads and few electrospunnanofibers formed from electrospinning a feedstock of 9% PVA andmucilage in a ratio of 30:70 (PVA:mucilage). The magnification in FIG.29 is 100×.

Example 3 9% PVA and Mucilage in a Ratio of 50:50 (PVA:Mucilage)

A 9% PVA solution and mucilage in a ratio of 50:50 (PVA:mucilage) wasused for electrospinning Although some deformities were present, fibersappeared to have much higher quality than those in Example 2. FIG. 14shows a microscopic image of electrospun nanofibers formed fromelectrospinning a feedstock of 9% PVA and mucilage in a ratio of 50:50(PVA:mucilage). The magnification is 100×.

Example 4 9% PVA and Mucilage in a Ratio of 70:30 (PVA:Mucilage)

A 9% PVA solution and mucilage in a ratio of 70:30 (PVA:mucilage) wasused for electrospinning Thin, flat-looking fibers formed that measuredabout 180 nm in diameter. FIG. 10 shows an SEM image of electrospunnanofibers formed from electrospinning a feedstock of 9% PVA andmucilage in a ratio of 70:30 (PVA:mucilage). The magnification is 11K×.FIG. 11 also shows an SEM image of electrospun nanofibers formed fromelectrospinning a feedstock of 9% PVA and mucilage in a ratio of 70:30(PVA:mucilage). The magnification in FIG. 11 is 100K×. For SEM images,the samples were sputtered with gold.

Overall, a larger amount of fibers were formed with fewer deformities,as compared to those in Examples 2 and 3. These results lead to theconclusion that at a higher PVA ratio more polymers were present inorder to start forming fibers with fewer deformities.

FIG. 12 shows an SEM image (magnification of 11K×) of electrospunnanofibers formed from electrospinning a feedstock of 9% PVA andmucilage in a ratio of 70:30 (PVA:mucilage). FIG. 15 shows a microscopicimage (magnification of 1000×) of electrospun nanofibers formed fromelectrospinning a feedstock of 9% PVA and mucilage in a ratio of 70:30(PVA:mucilage).

Example 5 11% PVA and Mucilage in a Ratio of 70:30 (PVA:Mucilage)

An 11% PVA solution and mucilage in a ratio of 70:30 (PVA:mucilage) wasused for electrospinning Many more fibers were produced than in Examples2-4. The fibers were measured as thin as 52 nm up to 8 μm and eventhicker. FIG. 16 shows a microscopic image (magnification of 100×) ofelectrospun nanofibers formed from electrospinning a feedstock of 11%PVA and mucilage in a ratio of 70:30 (PVA:mucilage). FIG. 17 shows a topview SEM image of electrospun nanofibers formed from electrospinning afeedstock of 11% PVA and mucilage in a ratio of 70:30 (PVA:mucilage).

FIG. 18 shows an SEM image (magnification of 70K×) of electrospunnanofibers formed from electrospinning a feedstock of 11% PVA andmucilage in a ratio of 70:30 (PVA:mucilage). A fiber measured 52 nm indiameter.

FIG. 19 shows an SEM image (magnification of 6K×) of electrospunnanofibers formed from electrospinning a feedstock of 11% PVA andmucilage in a ratio of 70:30 (PVA:mucilage). A fiber measured 7.8 μm indiameter.

Example 6 9% PVA and Mucilage (70:30 PVA:Mucilage) at Low MolecularWeight

A feedstock of 9% 28.4 M PVA and mucilage in a ratio of 70:30(PVA:mucilage) was used for electrospinning FIGS. 20A and 20B show AFMimages at 10 μm of electrospun nanofibers produced using this feedstock.FIGS. 21A and 21B show AFM images at 1 μm of electrospun nanofibersproduced using this feedstock. FIGS. 22A, 22B, and 22C show an AFMSectional Analysis at 1 μm of these electrospun nanofibers. From thesectional analysis, a fiber diameter measurement of about 177 nm wasobtained, which is very close to the previous measurement of 180 nmobtained from a previous mixture using an SEM image.

FIG. 27 shows a 3D AFM image at 1 μm of electrospun nanofibers using thefeedstock of 9% 28.4 M PVA in a ratio of 70:30 (PVA:mucilage). Thefibers appear to be very smooth with low porosity. This might change ifPVA is removed.

Example 7 9% PVA and Mucilage (70:30 PVA:Mucilage) at High MolecularWeight

A feedstock of 9% 80 M PVA and mucilage in a ratio of 70:30(PVA:mucilage) was used for electrospinning FIGS. 23A and 23B show AFMimages at 10 μm of electrospun nanofibers produced using this feedstock.FIGS. 24A and 24B show AFM images at 1 μm of electrospun nanofibersproduced using this feedstock. FIGS. 25A, 25B, and 25C show an AFMSectional Analysis at 1 μm of these electrospun nanofibers. From thesectional analysis, a fiber diameter measurement of about 460 nm wasobtained.

FIGS. 26A, 26B, and 26C show an AFM Sectional Analysis at 1 μm of adifferent sample of electrospun nanofibers produced using a feedstock of9% 80 M PVA and mucilage in a ratio of 70:30 (PVA:mucilage). From thesectional analysis, a fiber diameter measurement of about 4 μm wasobtained.

The AFM images show that this feedstock produces a bigger mix of fiberswith different diameters than the feedstock of Example 6. The diametersare overall much larger than the fibers of Example 6.

FIG. 28 shows a 3D AFM image at 1 μm of electrospun nanofibers using thefeedstock of 9% 80 M PVA in a ratio of 70:30 (PVA:mucilage). The fibersappear to be very smooth with low porosity. This might change if PVA isremoved.

Example 8 NaOH and Water Washes

PVA was removed from the nanofiber structures. This is done so that puremucilage fibers can be obtained. The experiment had positive results.FIGS. 31A and 31B show views of the pretreated mesh.

First, a 0.5 M NaOH wash was performed on a PVA-only and a PVA-mucilagenanofiber mesh and set to dry over 24 hours in an oven at 30° C. TheNaOH seemed to remove the PVA particles but crystalline formations wereobserved after drying in both meshes. FIG. 32 shows a microscopic image(20× magnification) of the crystals and the still intact mucilage mesh.

Next, a second set of experiments were performed with just deionizedwater on the PVA-only and PVA-mucilage mesh. The water seemed to washaway all the PVA since no nanofiber structures were seen in the PVA-onlymesh. Nanofibers were still intact in the PVA-mucilage mesh although themesh seemed to lose most of its content. This was expected since 70% ofthe mesh is composed of PVA. FIG. 33 shows microscopic images of puremucilage nanofibers (magnification in FIG. 33A is 50× and in FIG. 33B is100×).

Example 9 DSC Test

A differential scanning calorimetry (DSC) test was performed onnanofiber mesh. PVA at 9% (w/w) alone gave a melting point of 222.53° C.Mucilage and PVA high molecular weight at 9% melting point was 214.89°C. Also, mucilage and PVA low molecular weight at 9% melting point was216.27° C.

Both PVA-mucilage mixtures were at a ratio of 70:30. These two mixtureshad a melting point difference of 2° C. which is not very significant.The pure PVA at 222.53° C. is higher than the other two samples but nota very considerable difference. Thus, the mucilage is lowering themelting point of the PVA nanofibers.

FIG. 34 shows a plot of heat flow as a function of temperature forPVA-neat (green line, lower-most on the plot), PVA-high molecular weightmucilage (black line, uppermost on the plot), and PVA-low molecularweight mucilage (red line, middle line on the plot).

All patents, patent applications, provisional applications, andpublications referred to or cited herein, and/or listed in theReferences section, are incorporated by reference in their entirety,including all figures and tables, to the extent they are notinconsistent with the explicit teachings of this specification.

It should be understood that the examples and embodiments describedherein are for illustrative purposes only and that various modificationsor changes in light thereof will be suggested to persons skilled in theart and are to be included within the spirit and purview of thisapplication and the scope of the appended claims. In addition, anyelements or limitations of any invention or embodiment thereof disclosedherein can be combined with any and/or all other elements or limitations(individually or in any combination) or any other invention orembodiment thereof disclosed herein, and all such combinations arecontemplated with the scope of the invention without limitation thereto.

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We claim:
 1. An electrospun nanofiber, comprising a cactus mucilage,wherein the cactus mucilage has a linear repeating chain of (1→4)-linkedβ-D-galacturonic acid and an α(1→2)-linked L-rhamnose with trisaccharideside chains of β(1→6)-linked D-galactose attached at O(4) of L-rhamnoseresidues.
 2. The electrospun nanofiber according to claim 1, wherein thecactus mucilage is Opuntia ficus-indica (Ofi) mucilage.
 3. Theelectrospun nanofiber according to claim 2, further comprising anorganic polymer.
 4. The electrospun nanofiber according to claim 3,wherein the organic polymer is polyvinyl alcohol (PVA).
 5. Theelectrospun nanofiber according to claim 1, further comprising anorganic polymer, wherein the organic polymer is polyvinyl alcohol (PVA),chitosan, polyethylene glycol (PEG), or poly lactic acid (PLA).
 6. Ananofibrous membrane, comprising at least one electrospun nanofiberaccording to claim
 1. 7. The nanofibrous membrane according to claim 6,wherein the cactus mucilage is Opuntia ficus-indica (Ofi) mucilage. 8.The nanofibrous membrane according to claim 6, wherein the at least oneelectrospun nanofiber further comprises an organic polymer, wherein theorganic polymer is polyvinyl alcohol (PVA), chitosan, polyethyleneglycol (PEG), or poly lactic acid (PLA).
 9. The electrospun nanofiberaccording to claim 1, in which the cactus mucilage has 55 sugarresidues.
 10. The electrospun nanofiber according to claim 1, in whichthe diameter is 10 nm to 10 μm.
 11. The electrospun nanofiber accordingto claim 1, in which the cactus mucilage has a xylose to arabinose ratioof about 1:2 in its peripheral chains.
 12. The electrospun nanofiberaccording to claim 5, in which the organic polymer and the cactusmucilage are present in a ratio of either 70:30 or 50:50 (organicpolymer:cactus mucilage).